You probably already guessed the answer begins: "It depends..."

When you start with an oil that is well filtered so it doesn't have any fruit, seed, or nut solids, it lasts better. In India, it is hot and there is little refrigeration. Butter spoils quickly, but ghee, butter oil made by clarifying butter and removing every bit of the water and dairy solids, is stored or saved.

Some delicate oils such as almond, walnut, grapeseed, sesame, go sour fast. Buy from a place with good turnover in exotic groceries; anything which has dust on it to start with is too old to store.

Soybeans have an enzyme which breaks down the fats when the bean is crushed, soy oil is a good one not to store. Also be aware that non organic oils concentrate the pestcides in the parent plant, a real problem with cotton seed and peanut oils.

Besides time, the three enemies of edible oil are light, heat, and oxygen. So, a glass or clear plastic container which is half full (so it has a large surface exposed to air) and stored in a place with uncontrolled temperature will oxidize or "go rancid" much faster than a metal container filled to the brim and stored refrigerated.

Every time the can is opened, more oxygen gets in, so pour from your stoirage container into a smaller bottle for use. It's still better to keep both refrigerated.

If you already have it and are wondering whether to make paint or salad dressing out of it, smell it when you first open the container. The fresh, not bitter or stale odor is a good sign it is still fresh and edible. When you heat it the first time, pay attention; a barely rancid oil has a tattletale aroma at this time which is different from fresh.

If you are getting ready to store it, the old wives' trick is to put some vitamin E oil in it before sealing, as an antioxidant. No one can afford to use too much!

Fresh, properly stored oils, the professional estimate is store up to one year. I have personally eaten properly stored olive oil much older than this with enthusiasm and no bad effects.

If you want to buy a gallon because of price or quality, consider co-oping the cost with friends and dividing it up into containers that will fit in your refrigerators.

Hope this helps. If you need more specific information, please fill me in on the details of your situation.

Thanking you

So I don't reuse oil from frying fish, for example.

First, I use peanut oil, it breaks down less than any other vegetable oil when you fry with it.

Second I clean it after frying by frying some potato chunks and then filter it through a coffee filter, or several, before storing it.

And because I am concerned about the breakdown, I DO store it in the refrigerator, in a light resistant can or container, this is a question of chemistry.

Millions of people have not done all these things, reused oil a lot and done- OK as far as we know. Some even store it in the cooking pot, with no care. Their fried foods don"t taste nearly as good as those made with clean oil.

Is this safe?

Your product sounds delicious.

http://www.peanut-shellers.org/index_files/PeanutOil.htm